Right now I am trying to use the Blink LED tutorial project to familiarize myself with Red Pitaya. I am hoping to build on the existing code and control the DAC ouput, for example outputting constant voltage on one of the analog output.

I have tried modifying the definition of dac_a and dac_b in the top file, but the output is always zero. I would really appreciate if someone could give me an example.

When I upgrade the tutorial project to Vivado 2016.2, then insert the above code into red_pitaya_top.v, generate a new bitstream from it, and load it on the Red Pitaya, I can measure 0.56V on channel A output and -0.9V on channel B, as expected.

Make sure that the bitstream was generated successfully. There is one additional step after upgrading that needs to be done, changing the red_pitaya.xdc, lines 134,135, to

Between 2013.3 and 2014.1 Vivado was changed from requiring a differential IO standard being defined for the XADC input pins to requiring a single-ended one. Using the wrong one leads to errors during implementation of a design and termination of the bitstream generation. It is just a formality, but getting it wrong leads to a failed build and no updated bitstream. The tutorial project was designed with Vivado 2013.3 and thus you need to do the change in order to build the project with a current version.

I can generate bitstream. i load bit into my redpitaya/tmp and run red_pitaya_top.bit.
But i can not get response signal generator in DAC1.
If i change TMDS_33 into LVCMOS33, i got error when generate bitsream like this comment below:

ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinn_i[0] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinn_i[1] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinn_i[2] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinn_i[3] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinn_i[4] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinp_i[0] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinp_i[1] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinp_i[2] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinp_i[3] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended
ERROR: [Drc 23-20] Rule violation (IOSTDTYPE-1) IOStandard Type - I/O port vinp_i[4] is Differential but has an IOStandard of LVCMOS33 which can only support Single-Ended[/code]